If you’ve looked up your home’s value online lately, you’ve probably seen very different numbers depending on where you look. Zillow, Redfin, Realtor.com — all the major real-estate websites give you an estimate of what your home might be worth. But just because a number looks fancy on a screen doesn’t mean it reflects what buyers would actually pay.
Here’s why.
What These Online Estimates Are
All of these platforms — Zillow, Redfin, Realtor.com and others — use automated valuation models (AVMs). They take public records, recent sales, and algorithms to guess what a home might be worth. But they do not walk inside your home. They have no direct insight into condition, upgrades, layout, or local buyer preferences.
Even the best of them only gets you a starting point, not a real price.
How Far Off Can They Be?
Let’s look at a real example to show how wildly these estimates can vary. The famous “Home Alone” house in Winnetka was just sold for $5.5 million in early 2025. Here’s what online engines price it today:
(The following data were extracted as of early February, 2026)
📍 671 Lincoln Ave, Winnetka, IL 60093
- Redfin estimate: $5,145,861
- Zillow Zestimate: $5,711,400
- Realtor.com estimate: $5,864,324
That’s a difference of over half a million dollars between the biggest sites!
Let’s check out another famous home in Chicagoland – home of our former president Barack Obama:
📍 5046 S Greenwood, Chicago, IL 60615
- Redfin estimate: $2,565,761
- Zillow Zestimate: $975,100
- Realtor.com estimate: $1,900,000
That’s a difference of over nearly $1.6 million, or 60% difference between the biggest sites!
This isn’t unusual — different algorithms, data sources, and update schedules mean that websites can produce significantly different values for the same property. Many sellers have noticed these inconsistencies firsthand — with some online estimates off by 10%, or even much more compared to actual sale prices.
Error Rates: Not as Precise as You Think
According to data on valuation accuracy:
- For homes not currently for sale, most online AVMs have a median error rate around 6–8% — meaning being off by tens of thousands of dollars is normal.
- Even for homes actively listed on the market, errors of 2–3% or more are common.
Put another way:
A home estimated at $400,000 could actually sell for $380,000 or $420,000 — or even farther out — and still be well within the typical “error range” these sites offer.
Why These Algorithms Struggle
Here’s what all of these services miss:
- Interior condition: Is the kitchen renovated recently? Does the HVAC need replacement? Public data doesn’t know.
- Upgrades & finishes: Luxury touches vs outdated rooms matter to buyers.
- Neighborhood dynamics: A block sitting in a great school district can perform very differently than the next street over.
- Demand-side factors: Buyer taste and interest vary week to week, and algorithms can’t see that.
In short: numbers from these sites are educated guesses — not reality.
But They Can Be Helpful — With a Grain of Salt
There’s nothing wrong with checking Zillow, Redfin, Realtor.com, or other sites to see how the market feels. These tools are free, easy, and give you a starting point.
But here’s the key: Never set your listing price based only on an online estimate.
Too many sellers treat these as gospel and end up:
- Overpricing and sitting on the market
- Underpricing and leaving money on the table
- Getting frustrated because “my Zestimate is higher than what buyers are offering”
What You Should Do Instead
A true Comparative Market Analysis (CMA) from a licensed local agent looks at:
✔ Actual sales in your neighborhood
✔ Condition, upgrades, and walk-through insights
✔ Local buyer demand and market timing
✔ Quality comps your home is being compared against
These human-informed valuations are far more reliable than any automated tool.
Bottom Line
Online estimates from Zillow, Redfin, Realtor.com, etc., are useful as a starting point — but they’re not accurate enough to price your home for sale.
If you want a real pricing range tailored to your actual property, we’re happy to provide a local agent valuation with no spam and no pressure — just honest insight that helps you make the best decision.
Start by filling out the form below!
